Abstract

Whatever the location of highways or high‐speed roads is (urban, suburban, country), we frequently encounter viaducts or bridges. Building noise barriers on viaducts is not a simple matter, mainly for 3 important reasons: aesthetic, safety and stability, and the problem of viaduct joints. Aesthetically, the wish is to reduce the height of the barriers. One also very often wishes to use transparent barriers: for that case, these reflecting materials can degrade the performance of the barrier, either due to the effect of parallel reflecting walls, or due to the reflections which occur with high sided vehicles passing close to these. One should then achieve a specific study of the shape and materials that have to be used in such an application, not forgetting that each case is different. Another important problem occurring with the barriers on viaducts is that, once the barrier is effective and reduces the noise originally coming from the traffic on a viaduct, one could listen back to the noise due to bad noisy joints, noise coming from below viaducts, and not protected with the barriers. This paper will present some measurements and design studies made in such situations.